It's well known that placebos, or fake medicine, often work better than the real deal. Some doctors secretly prescribe them to problem patients when nothing else is working. But what happens when the patient knows they're taking sugar pills?

In a study published today in PLoS One, researchers compared two groups of patients with Irritable Bowel Syndrome: those who were left without treatments, and those given a twice daily dose of placebo. Author Ted Kaptchuc says:

"Not only did we make it absolutely clear that these pills had no active ingredient and were made from inert substances, but we actually had 'placebo' printed on the bottle. We told the patients that they didn't have to even believe in the placebo effect. Just take the pills."

Despite this, the patients taking the sugar pills saw a significant improvement of their condition, with 59% reporting adequate symptom relief, compared to 35% with the control. On other recorded outcomes, the placebo patients had a rate of improvements equivalent to those seen with powerful medication for the disease.

The study is self-admittedly small, only 80 patients, and doesn't compare people who knew they were taking a placebo to those who were unaware, but it will hopefully allow further research into this strange phenomenon.